Is It Me or my HD4 PRO

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Is It Me or my HD4 PRO

Postby o2manyfish » Tue Oct 01, 2019 7:08 pm

Hi Everyone,

I'm not an everyday CNC user. And I am entirely self taught. I have been making parts for about 2 years mostly out of Acrylic. When I started I understood there was a learning curve, and it taking me 4 to 6 times of building a piece to get it correct was part of that.

But now 2 years later, I still have to repeat make at least 75% of the pieces I try to make.

And I don't know now if it's me, my ability to understand, my unit, or my controller.

Here are my issues. My unit is out in the garage, when it gets hot in the summer time the controller freezes (bad choice of words) and it needs to be reset several times before playing nicely. Sometimes it freeze when loading the file, sometimes after the files runs, and of course sometimes mid run.

I am doing really simple things - cutting profiles and today a few pockets.

Here are the issues I had today:
1) Cut 2 Identical pieces of 24x10x1/4 abs (from the same full sheet) on each piece there are 3 2x3 pockets that are supposed to be .11" deep. First run cut fine. Second run the machine went nuts cut some other shape and then buried the bit into the table snapping the bit. It buried the bit in the middle of the table and there was nothing the gantry could have bumped into. The material is .245 thick, I was cutting a .245 depth on the profile and I have a piece of 5/8 MDF under the material. When the head buried into the table it slowly went from the .245 to the snapping of the bit over about 7 inches and it's a smooth depth increase - so clearly the controller was controlling the head down.
2) After I remade the second piece with no errors - I discover the pockets are 3 different depths. I pulled out my calipers and between the sample run (on mdf) and the 2 pieces out of ABS only 3 out of 9 pockets are the correct depth. The pocket bottoms are smooth an even cut. So the machine cut the entire 2"x3" pocket at the wrong depth.

I then cut 4 more pieces of just the profile with no pockets. These pieces are 24x10 by 1/4. Each piece was cut with 4 tabs to hold it in place and material was clamped and screwed down. 2 of the pieces on the long 24" cut aren't straight lines. What bothers me most about this is that I took 2 passes to cut the profile and both passes have the same error, but it's not in the code because the other pieces don't have the same "oops"

And now I have 6 pieces of material all cut using the same profile code to cut the shape. And yet none of them are the same size.

If I tell the machine to cut me 6 24x10 rectangles - shouldn't I get 6 identical rectangles, or maybe 5... But I cut 9 pieces of material today to get the 6 I need and the final 6 aren't the same size?

Is it me? Am I expecting too much from the unit? I mean I am not asking for .0001 tolerances from piece to piece - But some of my pieces are .25" different from one to the other. And the pocket cuts that were supposed to be .11" deep vary from .13 to .20 to .08

If it's me - don't worry about offending me... I just need to learn what it is I am doing wrong.

Thanks

Dave B
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Re: Is It Me or my HD4 PRO

Postby jeb2cav » Wed Oct 02, 2019 6:47 am

Hi Dave,

It could be a combination of 'things' that is contributing to this. From your detailed description, I don't think it is any one of these, but 2 or more. I also run a Shark in the environment as is, and have been for several years.

1 - job runs but sizes are different. Almost guarantee that one or more of your lead screws are not securely attached to the motor. If this is loose, even a little, you can get the appearance of a good cut one time, and then different on another. Of course you have to take the table off to check one of them. The opportunity for these to be loose is even higher in your case as you've had the bit engage the table while the machine is running. You want to ensure the lead screw flat end is facing the locking bolt. I use a dab of wood glue as some insurance (do not use a strong screw lock paste).

2 - pockets different height - again, lead screw, but also tool not secure in collet, and more typically router not secure in gantry.

3 - random machine behavior - in my case, this was caused by poor power in my shop. The power voltage varied, as did the amperage. I put a small office UPS in front of all power use by my shark. I did this primarily to condition the power - the battery back up is about 5 minutes. Since I've done that, any unexpected outcomes have been user error or mechanical for me.

4 - I do believe you can overheat the control box. My shop can get up to 115, but typically doesn't exceed 98 for long periods of time. I have a small fan running to ensure the air around and behind the controller is at least moving.

5 - there's always the chance of loose electrical connections - be sure your cables are well attached to the controller, as well as the pendant.

Hope one or more of these ideas helps.
jeb2cav
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Re: Is It Me or my HD4 PRO

Postby sharkcutup » Wed Oct 02, 2019 8:54 am

https://www.cncsharktalk.com/viewtopic. ... 786#p30786

The above link I believe may be of interest/help.

The lead screws not being tight are a significant cause of most alignment/consistency problems. Check yours to make sure they are seated on the flat of the lead screw and they are tight.

Optimized-x-axis lead screw.jpg

x-axis lead screw

Optimized-y-axis lead screw.jpg

y-axis lead screw

Optimized-z-axis lead screw.jpg

z-axis lead screw

Note: Images ABOVE are of Shark HD3 Pro Extended Bed CNC Machine

Still have no idea as to why images get flipped around --- Sorry!

Sharkcutup
Shark HD3 Pro Plus Extended Bed with Water-Cooled Spindle
Facebook: hoganscnccrafts.com
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Re: Is It Me or my HD4 PRO

Postby sharkcutup » Wed Oct 02, 2019 9:14 am

You may want to look also at your bed surface in relations to the Gantry (z-axis (depth inconsistency)).

If this bed surface is not parallel to the gantry then your material board sitting on that surface is not parallel to the gantry. In most cases this is solved by the adding of a spoil board (Usually MDF) to the bed surface and planing its surface to the gantry (Z-axis). There are several Youtube videos on YouTube.com that show how this is done. Adding and surfacing a spoilboard to the cnc surface bed usually minimizes the inconsistencies of depth variations.

Sharkcutup
Shark HD3 Pro Plus Extended Bed with Water-Cooled Spindle
Facebook: hoganscnccrafts.com
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Re: Is It Me or my HD4 PRO

Postby o2manyfish » Wed Oct 02, 2019 5:48 pm

Let me first say a "Big Thank YOU" to those that posted to help.

I started with the set screws on motors - but 2 out of 3 were locked in and tight. I did not get to the Y screw under the table but the Y variances were not as much as X and Z.

Based on the post about planing a piece of MDF to level the table I grabbed a 5' level and found that the table was nice and flat.

I then ran a test cut. I cut a 22x1x.01 rectangle. And when I did this I saw that the cut started correctly and then got much deeper at the middle of the table and then went back to shallow at the far end and then repeated on the way back.

I started checking everything and noticed that the base of the machine is no longer flat. It has warped and the flat bottom panel now arches up over 1/4".

It's on a steel work bench - which I know is level. In my garage I actually have the back of the unit facing me because it makes it easier for me to to load the materials. I put some shim material under the Front edge changing the point where all the weight was resting.

This slight change got the .01 rectangle cut so close to the correct depth from front to back that I had to measure it to make sure that it wasn't perfect. I'm hoping that a couple of days with the shims and the weight will sag the unit back to 'more' straight and that might take care of the level issues.

I'm going to pickup a UPS for the controller. Thats a good bit of advice.

Thank you again for those that gave me the ideas of where to start looking.

Dave B
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